1. Field of the Invention
This invention relates to press tooling for manufacturing outer or inner members of constant velocity ratio universal joints by deformation of workpieces. Particularly it relates to the manufacture of members for universal joints of the type wherein ball-receiving tracks in the members, spaced circumferentially about the members, are of non-undercut configuration.
In the context of an outer joint member, which is in the form of a hollow component having an open end, in referring to the ball-receiving tracks as being non-undercut we mean that the base of each track is, at a position away from the open end of the joint member, not at a greater radial distance from the rotational axis of the joint member than it is at such open end. In the context of an inner joint member, in referring to the ball-receiving tracks therein as being non-undercut we mean that, considered from one end of the member, the distance of the base of each track from the rotational axis of the member increases to a maximum but does not then decrease with increasing distance from the said end of the member.
Between the ball-receiving tracks of the joint members, the members have respective portions of a surface which may serve for guiding a cage in the completed joint and which may be of part-spherical configuration. Such part-spherical surface portions are not, of course, non-undercut.
2. Description of Prior Art
One form of press tool for forming joint outer members is known from DE-2830275, the tool comprising an inner mandrel or expander element with a conical end region, and a number of segments disposed therearound and movable axially relative thereto. The segments have external surfaces which may be part-spherical to form part-spherical surface portions of the interior of the outer joint member, and internal surfaces which co-operate with the expander mandrel. In use, the material of a workpiece is deformed around the tool while the mandrel is holding the segments in their expanded condition, by pressing the workpiece in or through a die. Thereafter the expander mandrel is withdrawn from the segments, permitting them to be displaced radially inwardly to disengage them from the surfaces formed thereby, after which they can be withdrawn from the finished article. One disadvantage of this design of tool is that when the segments are in their expanded condition gaps exist therebetween, into which the material of the workpiece can flow during its deformation. Subsequently, machining is necessary to remove such material.
A similar tool is known from DE-3004024, which differs slightly in that the segments of the tool are shaped to form part of the ball-receiving tracks as well as the cage guiding surfaces. The dividing line between each adjacent pair of segments of the tool is positioned in the centre of a ball-receiving track. This tool also has the disadvantage that it is necessary subsequently to machine the ball tracks of a joint member produced by it.